AdSense

AdSense is a cost-per-click (CPC) ad serving system created by Google. Users can sign up for free and start showing ads across the Google Network by inserting a piece of code onto their web pages. The HTML code can be modified so that ads match the specific color, fonts and style of the web page they appear on. Every time someone clicks on your ad, you earn money.

Controversy

Click fraud has been a major criticism of the Google ad systems and in 2006, Google settled a suit in Arkansas for $90 million resulting from advertisers being charged since 2002 for fraudulent clicks (Fox News, July 2006). In March, 2007, Google released a CPA (cost-per-action) advertising system so that advertisers pay only when users complete a pre-determined goal, such as buying a product or signing up for a newsletter, instead of paying per click.

Another issue with AdSense has been the creation of web sites for the sole purpose of earning ad revenue. A web site owner registers a new domain, adds keyword-stuffed content, starts a link building campaign (usually using black hat methods) and installs AdSense to the site. At one point, some of these domains ranked above search results that were more useful, however Google has since made advancements in how they rank web sites and most of these are filtered out.